Earlier we talked about some optional elements of the network video server. In this article, we will continue to talk about how to purchase a network video server. What should we pay attention to when purchasing a network video server?
When purchasing a network video server, we should pay attention to the following factors:
Factors influencing the purchase of a network video server: IE monitoring function
Conventional monitoring and management software is used to achieve the integrity of the function, the operation is cumbersome and inconvenient, and even requires special training and learning to be proficient. The management software provides a simple WEB version of the monitoring management software selection suitable for leading or non-professional monitoring managers. It can provide single screen image monitoring, recording, control and other functions in the form of IE webpage. Users do not need to install professional software. When monitoring image selection, there is no need to memorize the complex IP address of different network video servers. Just access the system's WEB server to download the configuration information control such as the preset monitoring point name. The mouse click to select the relevant image name to realize the monitoring function.
Factors influencing the purchase of a network video server: the number of frames transmitted by the image
Currently, network video servers on the market can support one or two or four video image inputs. Since the number of supported image channels is higher, the requirements for product technology and processing performance are higher, so most products are single-channel or "quasi-multi-channel" products. What we call a true multi-channel network video server that can support 25 frames per second of digital video images is truly "real time". The "quasi-multi-channel" product, regardless of two or four channels, has a total frame rate of 25 frames per second for digital video images, that is, multiple frames of 25 frames per second, in image processing technology and single-channel products. There is almost no difference. This point can be easily judged from the price. The price of single-channel and two-way products of some manufacturers differs by only a few hundred yuan. Basically, it can be judged that the two-way products are “quasi-two-way productsâ€.
Factors influencing the purchase of network video servers: image compression algorithm standard
The current mainstream network video server compression algorithm standards are nothing more than MJPEG, MPEG-1, MPEG-4.
The MJPEG compression technology standard is derived from JPEG image compression technology and is a simple intraframe JPEG compression. The image clarity is better after compression. However, due to the technical limitations of this method, it is impossible to make a large proportion of compression, the data volume is high, and the recording is 1-2G space per hour. The network transmission consumes a large amount of bandwidth resources, which is not suitable for the compression of moving object images, nor is it large. Applicable to the needs of domestic long-term security video recording.
The MPEG-1 compression technology standard adopts the compression algorithm of multi-frame prediction before and after frame. It has great compression flexibility and is the most widely used. This algorithm technology is mature, and the data compression rate is higher than MJPEG, but the data volume is still relatively large. The video is 300-400M per hour. If it is used for long-term real-time video recording by the bank, it takes up a lot of hard disk space, especially the network transmission occupies a large bandwidth, which is not really used for remote transmission of video images.
The MPEG-4 compression technology standard is the most advanced compression technology currently in the practical stage. It uses a very narrow bandwidth to compress and transmit images through frame reconstruction technology to obtain the best image quality with the least amount of data. The characteristics of MPEG-4 make it more suitable for interactive AV service and remote monitoring. It adopts MPEG-4 compression algorithm, and the image compression is relatively high. The video is 100-200M per hour, the image clarity is high, and the network transmission occupies a small bandwidth. Various transmission methods for remote video image transmission.
Factors influencing the purchase of a network video server: the number of video channels that the monitoring center can simultaneously monitor and record.
Since the network video monitoring server is mostly used for remote, real-time and centralized monitoring of multiple distributed network points, the number of video channels that the monitoring center can simultaneously monitor and record is an important indicator for measuring the effect of remote centralized monitoring. In theory, remote real-time monitoring and recording can be performed on an unlimited number of monitoring target images at the same time. However, in actual applications, the actual network bandwidth of the monitoring center is limited. For example, if the central network bandwidth is 10M, assuming that each video occupies 250K, a maximum of 40 video recordings can be achieved unless the video bandwidth is increased or the network bandwidth is increased.
Factors influencing the purchase of a network video server: How to effectively support multiple users accessing the same monitoring front end at the same time
In a large-scale network video centralized monitoring system based on a network video server, the monitoring center usually sets a plurality of monitoring clients, and often has access to a front-end monitoring network point and issues a real-time monitoring or recording call request in the same time period. When there are N monitoring clients in the monitoring center that need to view a remote monitoring point image at the same time (assuming that the image bandwidth of one channel is 250K), the bandwidth of the external network in normal mode is (N*250)K, which usually leads to data jam. Affect the monitoring effect, so the conventional network video server system can only support the simultaneous access requirements of three or four clients.
Factors influencing the purchase of a network video server: Whether to support remote online intelligent retrieval, playback and transcription of local video data
For the remote, real-time, centralized monitoring system application of multiple distributed network points, due to the scarcity and compensation of the current public network bandwidth resources, most users will use ADSL broadband lines for remote digital video signals for economic reasons. transmission. At present, the theoretical bandwidth of the monthly ADSL line provided by the telecommunications department is 512K for the uplink bandwidth and 2M for the downlink, but the actual uplink bandwidth is often only 200K. In order to fully meet the needs of monitoring applications, the actual system uses the function mode of “central remote real-time round robin monitoring, local real-time video recording of the network, and remote monitoring of the video at any timeâ€.
For remote viewing applications of local video data of outlets, most network video server software currently cannot provide an effective solution. Most local staff select the required video data files and remotely copy or E-MAIL to the central monitoring personnel. The central monitoring personnel will open and watch after receiving it, which is cumbersome and time consuming.
Factors influencing the purchase of a network video server: Whether to support automatic connection in a dynamic IP network environment
In the network application environment based on the ADSL broadband line, the access mode provided by the telco to the user is the dynamic IP access mode, that is, the way that the user dynamically obtains the IP address through the virtual dialing technology to access the Internet: the dialing program installed by the user through the local computer When driving ADSL Modem dial-up access to the INTERNET, the ISP usually randomly assigns the user a public IP address. This IP address is unique before the disconnection. Other users can access the user through this IP address, but once disconnected, When connected again, the ISP will re-allocate another IP address to the user.
In the remote video centralized monitoring application using the network video server, how to easily realize the real-time access of the monitoring center to the monitoring front end under the dynamic IP address condition in the network application environment based on the ADSL broadband line is still plaguing many engineering companies. One of the challenges of system integrators and network video server manufacturers. At present, many network video servers cannot provide a solution for dynamic IP access. Once an engineering company or user utilizes a network video server and establishes a remote monitoring system through ADSL, it is likely that the system cannot achieve the desired function.
Factors influencing the purchase of a network video server: Is there an ADSL automatic dialing function?
Conventional ADSL broadband applications must be dial-up via a computer connected to the ADSL Modem. However, if the ADSL is only used for remote monitoring access, then configuring a computer for each monitoring front end for a simple ADSL dialing function will undoubtedly cause a great waste of user equipment resources. Under the above circumstances, whether or not the ADSL automatic dialing function will directly affect the user's investment budget.
Factors influencing the purchase of a network video server: Is it possible to integrate the monitoring system with other management systems?
In some system applications, the video surveillance system is only an application subsystem of the entire large-scale system. If the video surveillance system can be organically integrated with other systems, it will greatly facilitate the user's system operation.
Factors influencing the purchase of a network video server: warranty issues
Warranty issues are one of the most important concerns for engineers. As the engineer directly faces the end user, the unsatisfactory warranty service will directly affect the reputation of the contractor.
How to buy a network video server is introduced to everyone here, I believe that after reading this article, the purchase requirements for the network video server will not be unfamiliar.
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